FIG. 1 depicts a conventional method 10 for fabricating a magnetoresistive sensor in magnetic recording technology applications. FIGS. 2-3 depict a conventional transducer 50 during fabrication using the method 10. FIGS. 2-3 are not to scale. The method 10 typically commences after a conventional magnetoresistive, or MR, stack has been deposited.
A conventional MR sensor is defined, via step 12. This typically includes providing at least a photoresist mask and may include the use of a hard mask. Forming the photoresist mask using conventional photolithography also typically includes using an antireflective coating (ARC) layer under the photoresist mask. The seed layer, hard bias layer, and hard bias capping layer are deposited, via step 14 and 16. FIG. 2 depicts an ABS view of the conventional transducer 50 after step 16 is performed. The conventional magnetoresistive stack 54 typically includes an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. Also shown is a capping layer 56. In addition, seed layer(s) may be used. The conventional magnetoresistive sensor 54 resides on an underlayer 52, which may be a substrate. Also shown is the photoresist mask 60. A seed layer 64, hard bias material(s) 66 and capping layer(s) 68 that form the hard bias structures are shown. Also shown is insulating layer 63 between the hard bias structure and the sensor 54. Capping layer(s) 68 typically include Ru and Ta sublayers and are currently on the order of about twenty nanometers or more in thickness. Also shown are fencing/redeposition 62A and 62B. The fencing/redeposition 62A and 62B are formed when the sensor is defined in step 12.
A chemical mechanical planarization (CMP) is performed, via step 18. The CMP performed in step 18 smoothes the topography, particularly that due to the photoresist mask 60 and fencing 62A and 62B. FIG. 3 depicts the conventional transducer 50 after step 18 is performed. The CMP is configured to remove fencing/redeposition 62A and 62B, and generally to planarize the conventional transducer 50. Thus, portions of the capping layers 56 and 68 have been removed, leaving portions 56′ and 68′, respectively. Photoresist mask 60 has also been removed.
Although the conventional method 10 allows the conventional transducer 50 to be fabricated, there are drawbacks. During and after the CMP performed in step 18, sensitive portions of the conventional transducer 50 may be exposed. For example, the hard bias 66′ shown in FIG. 3 may be subjected to corrosive chemicals. The materials used in the hard bias structures and the topology shown in FIG. 2 may result in uncontrolled removal of portions of the hard bias structure, such as the capping layer 68, near the sensor 54. As a result, corrosion 70 may be formed. The corrosion 70 may degrade the performance of the hard bias 66′ and thus the conventional transducer 50. Corrosion that also adversely affects performance might also exist in the free layer, pinned layer, and pinning layer (not specifically delineated in FIGS. 2-3). As the conventional read sensor 54 becomes narrower and/or the stripe height (perpendicular to the plane of the page in FIG. 3) shorter, such issue may increase in frequency and/or severity.
Accordingly, what is needed is a system and method for improving the fabrication of a magnetic recording read transducer.